Can we use json_serializable package to serialize and deserialize user models?

Question

After generating part 'UserModel.g.dart'; successfully, I got the following error upon trying to do

if (user != null) {
      var uid = user.providerData.first.uid;
      var displayName = user.providerData.first.displayName;
      var email = user.providerData.first.email;
      var phoneNumber = user.providerData.first.phoneNumber;
      var providerId = user.providerData.first.providerId;
      var photoUrl = user.providerData.first.photoURL;
      UserModel userModel = UserModel(phoneNumber,
          uid: uid,
          displayName: displayName,
          email: email,
          providerId: providerId,
          photoUrl: photoUrl);
      Query query = users.where('uid', isEqualTo: uid);
      query.get().then((querySnapshot) => {
            if (querySnapshot.size < 1) {addUser(userModel)}
          });
    }
  }

And here is my UserModel.dart without any errors in the file.

import 'package:json_annotation/json_annotation.dart';

part 'UserModel.g.dart';

@JsonSerializable()
class UserModel {
  late String? uid;
  late String? displayName;
  late String? email;
  late String? phoneNumber;
  late String providerId;
  late String? photoUrl;

  UserModel(this.phoneNumber, {required this.uid, required this.displayName, required this.email,
      required this.providerId, required this.photoUrl});
  factory UserModel.fromJson(Map<String, dynamic> json) => _$UserModelFromJson(json);
  Map<String, dynamic> toJson() => _$UserModelToJson(this);
}

Offcourse, I could manually map each value. But as recommended here https://flutter.dev/docs/development/data-and-backend/json, to prevent

Manual decoding does not perform well when your project becomes bigger. Writing decoding logic by hand can become hard to manage and error-prone. If you have a typo when accessing a nonexistent JSON field, your code throws an error during runtime.

I used the plugin json_serializable to sort of automate it. But I got the following error: Expected a value of type 'Map<String, dynamic>', but got one of type 'UserModel$'

Is this error expected due to incompatibility or am I doing something wrong? Please respond. Thank you very much. :)

Answer 1

I'm guessing this is where your issue is.

 query.get().then((querySnapshot) => {
            if (querySnapshot.size < 1) {addUser(userModel)}
          });

Use the toJson method you created in your model class to pass in a Map instead of your custom UserModel object.

 {addUser(userModel.toJson())}